Yeah, really good history here.
It was a class trip and we were on some walking tour around historic Boston. The tour guide was dressed as James Otis and we had to yell Huzzah! a lot. We were by some church and there was this really large hole in the ground covered by a metal and brick case. He started telling us this weird story about murders and other conspiracies as to what the hole was.
Then he said to forget all that because it's just a vent for the subway system.